1. Field of Invention
This invention relates generally to roof-bearing plates to firmly secure a layer of thermal insulation material to a roof surface, and more particularly to a plate of this type which is embossed to create a plate-reinforcing pattern which acts to resist flexure of the plate.
It is common practice to cover the roof of a building with a layer of thermal insulation material. This layer may be formed of pads of light-weight material such as fiberglass which are laid down on the surface of the roof and covered by a sheet of polyvinyl chloride or tarred cardboard to protect the layer against water penetration.
Since the roof is exposed to the elements, it may at times be subject to high velocity winds, as high as 150 miles per hour. Unless the insulation layer is firmly secured to the roof, the resultant updraft may blow the insulation layer from the roof. One cannot as a practical matter use bonding agents to adhere the layer to the roof, for these lack sufficient strength to resist strong updrafts. It is therefore the usual practice to secure the layer to the roof by load-bearing plates of sheet metal which lie over the layer and are bolted or otherwise fastened to the roof.
2. The Prior Art
The patent to Williams, U.S. Pat. No. 1,286,862, shows a contoured roofing washer designed for a corrugated iron roof, the washer having a center hole from which radiate triangular ribs.
The patent to Sandqvist, U.S. Pat. No. 4,074,501, shows a heat insulating layer on a roof which is held thereto by plastic plates having a center bore to receive a screw.
The patent to Carlson et al., U.S. Pat. No. 4,288,951, provides insulation for the roof of a metal building or mobile home, use being made of a self-locking washer to sandwich the insulation panel between the fastener and a base plate. This patent is of interest because of the configuration of the radial ribs on the washer which extend between the center hole and a marginal rectangular rib.
The DeCaro patent, U.S. Pat. No. 4,361,997, shows a plastic plate to secure insulation to a metal roof. The configuration shown in FIG. 3 is of particular interest because of the triangular ribs radiating from a center hole at the bottom of the plate. These ribs are intended for anti-rotational purposes.
Other forms of plates to hold insulation to a roof are shown the Kelly U.S. Pat. Nos. 4,162,597 and 4,389,826. Of lesser interest are the following U.S. Pat. Nos.
______________________________________ 4,161,087 3,101,763 4,329,821 2,769,333 4,075,807 3,370,631 3,478,639 ______________________________________